Blackboard



G. W. PETTIS June 6, 1939.

BLACKBOARD CEILING j Filed July 5, 1938 INVENTY) Patented June 6, 1939 UNITED STA -Es PATENT OFFICE 5 Claims.

This invention relates to .blackboards and in .particular it relates to a blackboard arrangement wherein multiple blackboard surfaces may be disposed in substantially the same location. In general, the invention comprises a'blac'kboard arrangement consisting of two blackboards each of which is reversible and each blackboard being arranged in counter-balanced relationship with the other permitting either of the blackboards to be positioned in substantially the same general location.

In the application of blackboards for school purposes, lecture rooms and court rooms it is desirable to limit the blackboard surfaces to relatively small areas. 7 Also, it isdesirable to preserve certain markings on blackboards for-limited times. In accordance with the practice of my'inven'tion I provide a blackboard arrangement in which any of four different blackboard surfaces may be easily and quickly positioned to within the same general area. Further, the present inventive embodiment may be constructed in the form of a movable unit or it may be built into the wall structure of a building.

It is, therefore, among the objects of the present invention to provide a blackboard arrangement consisting of multiple blackboard surfaces .any of which may be, readily positioned in a given area and which arrangement is consistent with simplicity of operation, economy of manufacture and applicable for use in the form of a unit or in the form of a built-in feature of a building.

These and other objects and advantages will appear more fully in the following detailed description when considered in connection 'with the accompanying drawing in which:

Fig. 1 is a front elevational view showing an illustrative embodiment of my invention;

Fig. 2 is a side elevational view thereof partly broken away to show the operation of the mechanism and showing the arrangement as applied in a wall construction which is shown in section;

Fig. 3 is an enlarged view in section taken along lines III-III of Fig. 1.

Fig. 4 is a plan view of a portion of the apparatus partly in section, the section being taken along lines IV-IV of Fig. l; and,

Fig. 5 is an enlarged fragmentary view of a portion of the apparatus shown in Fig. 1.

Referring to the drawing and in particular to Figures 1 and 3, the improvement of my invention includes rectangular frame I which is made of structural steel having a channel shape in crosssection. The projecting legs formed by the channel I extending inwardly relative to the rectangular frame so that the legs form track members, the operation of which is described hereinafter. Essentially the blackboard arrangement is in the form of two units 2 and 3, each of which is substantially similar to the other. The units 2 and 3 are supported by cables a cords '4 which attach to the unit and loop over pulleys "5 rotatably mounted on a shaft "6 supported by the frame I. Collars I are attached to the shaft 6 for locating same relative to "the frame I. The pulleys 5 are freely rotatable about the shaft "6 and their axial position on the shaft '6 is maintained in accord ance with the location of the cables.

the blackboard unit 2 and the blackboard 'unit '3 are substantially identicalin construction, onlyone unit will be described and it is intended that similar reference numerals may be. used 'interchangeably to designate the same parts on the different units.

The blackboard unit 2 is supported by a carriage which consists essentially of horizontal rods "8 and 9 and vertical straps Ill and II which are rigidly attached to the rods 8 and '9 and which maintain the rods in fixed spaced relation. At each end of the rod '8 and attached thereto by means of nuts I2 is a pair of brackets, 13 and I4 (Fig. 4) which form a yoke for supporting a grooved wheel I5. A pin I6 extends through the brackets 13 and I4 to form a bearing for the wheel I5. The Wheel I5 islocated in a manner to ride on a leg of the frame 'I which serves as a track for engagement with the wheel I5. A similar pair, of bracketsand wheels are attached to the rod 9. As thus described the rods 8 and 9, straps I and II and wheels I provide a carriage which is restricted to vertical movement along the leg member of the frame channel.

Link members I1 and I8 are .pivotally mounted 'on the horizontal rod 8 and serve as a means to which the cables! are attached. Also secured to the link members l1 and I8 is a yoke member I9 pivotally attached at 20 to a frame '2I of a double surface blackboard '22. By this arrangement and as shown in Fig. '2, the blackboard may be swung on its pivots 20 so that the blackboard surfaces may be reversed. During this swing movement the yoke member I9 moves outwardly to permit the blackboard to clear the straps II] and II. .In order to facilitate swing movement of the blackboard rollers 23 (Fig. 5) are secured to the frames of the blackboard. These rollers are positioned so that they may engage with the flat surface of the straps I0 and I I. The rollers 23 maybe attached to the blackboard frame 2I by means of metal clips '24 secured to the frame by wood screws 25. Preferably, the rollers 23 are composed of resilient material so that the blackboard frame will rest upon the strap members I0 and 'II through the medium of a resilient material. For convenient manual operation of the blackboard a handle 26 is attached to the lower portion of the frame 2I. V r

In order to prevent loose contact engagement of the blackboard through its rollers 23 with the strap members I 0 and II, I provide a torsion spring 21 (Figs. 3 and 4) which is wound around the rod 8 and having one end engaging with the strap member ID or I I and the other end engaging with the horizontal portion of the yoke member I9. By the application of this spring a tension is exerted against the yoke member I9 with the result that the rollers 23 attached to the frame 2| are pressed firmly against the strap members I and II. The spring 21 is of sulficient resiliency to permit the yoke member I9 to move outwardly during the reverse swing movement of the blackboard. For example, when it is desired to reverse one of the blackboards, the operator grasps the handle 26 and moves the lower part of the blackboard outwardly while the upper portion of the blackboard remains pivotally against the straps ID and II. The swinging movement of the blackboard, through the pivot '20, carries the yoke member I0 outwardly against the action of the spring 21 thus forming a sup=-' port for the blackboard while it is being turned on its axis. When the reverse movement is completed the spring 21 maintains the blackboard in tight engagement against the straps Ill and I I. As each unit 2 and 3 is of equal weight they operate to counterbalance each other and the friction of the difierent contacting parts serve to offer sufiicient resistance to maintain the different units in the position in which they are manually placed.

As shown in Fig. 1 the lower blackboard or unit 3 is assumed to be at a convenient elevation for providing a serviceable blackboard surface. While in this position the upper blackboard or unit 2 should be in a position which is at least sufficiently above the unit 2 so that the upper unit will not cover any part of the serviceable surface of the blackboard. When the exposed surface of the lower blackboard unit 3 has been chalk-marked, a new surface may be presented by the operator by merely grasping the handle 26 and pulling the blackboard forward and up as shown in Fig. 2. This operates to reverse the blackboard surfaces. When this reversed surface of the blackboard becomes chalk marked a further blackboard surface may be presented by grasping the handle 26 and moving the entire unit 3 upwardly thus permitting the blackboard unit 2 to move downwardly in substantially the same position as that previously occupied by the blackboard unit 3. When this blackboard surface becomes chalk marked a still further blackboard surface may be presented by swinging the blackboard to expose its reversed side as previously described.

As shown in Fig. 2 the blackboard arrangement may be embodied into a wall construction. To accomplish this a wall surface 28 may be attached or placed in front of the frame member I allowing sufficient clearance for the grooved wheels I5. An opening 29 is provided through the wall 28. This opening may correspond substantially in size with the size of one of the blackboard surfaces. A chalk molding 30 may be used at the lower margin of the opening 29.

While I have thus shown and described a preferred embodiment of my invention it is to be understood that I contemplate such modifications which appear obvious and which appear within the scope of the appended claims.

Having thus described my invention what I claim is:

1. In a device of the character described, a pair of blackboard frames, a double surface blackboard mounted in each frame, a pair of vertically movable carriages, a vertical track including a support positioned in cooperative relation with each carriage, wheels attached to the carriages for engaging the tracks, means for connecting the frames in vertical movable relation with the support, whereby one of the frames supporting a blackboard counterbalances the other frame and blackboard, and means for pivotally reversing either of the blackboard frames comprising a yoke pivoted at its upper end to the carriage and pivotally supporting the blackboard in a horizontal axis.

2. In a device of the character described, a pair of blackboard frames, a double surface blackboard mounted in each frame, a pair of vertically movable carriages, a vertical track including a support positioned in cooperative relation with each carriage, wheels attached to the carriages for engaging the tracks, a bracket pivoted to the carriage and pivoted to the frame at the vertical center of the frame, and means for connecting the frames in vertical movable relation with the support, whereby one of the frames supporting a blackboard counterbalances the other frame and blackboard.

3. In a device of the character described, a pair of blackboard frames, a double surface blackboard mounted in each frame, a pair of vertically movable carriages, a vertical track including a support positioned in cooperative relation with each carriage, wheels attached to the carriage for engaging the track, a bracket pivoted to the carriage and pivoted to the frame at the vertical center of the frame, pivotal means for supporting the blackboards, and resilient means for normally maintaining the blackboards in substantially rigid relation with the carriages.

4. In a device of the character described, a pair of blackboard frames, a double surface blackboard mounted in each frame, a pair of vertically movable carriages, a vertical track including a support positioned in cooperative relation with each carriage, wheels attached to the carriage for engaging the track, a bracket pivoted to the carriage and pivoted to the frame at the vertical center of the frame, pivotal means for supporting the blackboards, resilient means for normally maintaining the blackboards in substantially rigid relation with the carriages, and means for pivotally reversing either of the blackboard frames.

5. In a device of the character described, a pair of blackboard frames, a double surface blackboard mounted in each frame, a pair of vertically movable carriages, a vertical track including a support positioned in cooperative relation with each carriage, wheels attached to the carriage for engaging the track, a bracket pivoted to the carriage and pivoted to the frame at the vertical center of the frame, tension means for normally maintaining the blackboards in substantially rigid relation with the carriages, means for pivotally reversing either of the blackboard frames, and rollers mounted on the frame and engaging with the carriage for facilitating pivotal, reverse movement of the blackboard frames.

GLENN W. PETTIS. 

